The present invention generally relates to resilient cushions or materials and a method of manufacturing same. More particularly, the present invention provides for the manufacture of articles having controlled resilient properties through the combination of various gels, foams and foaming agents.
The properties of gel/foam combinations are important in a variety of manufactured items. For example, resilient cushion materials find application in numerous toys, bicycle seats, therapeutic hand exercising grips, shock absorbers, acoustical insulators, vibration dampers, wrappers, hand exercisers, crutch cushions, cervical pillows, bed wedge pillows, leg rest cushions, neck cushions, bed pads, elbow pads, elbow pads, wheelchair cushions, and many pads including floor pads, orthopedic shoe soles, brace cushions and numerous other objects of manufacture.
An article formed from the combination of gel and foam can have its resilient properties tailored through the use of foam of different sizes as well as resiliency depending upon the use and function of the resulting article.
As an example, foam pore size may have a significant influence on a composite resiliency. A discussion of gel foam combinations may be had from U.S. Pat. No. 5,633,286, which is incorporated herewith by the specific reference thereto, for describing the advantages of a gel/foam combination article.
A method for making a resilient cushion, which may take the form of any of the hereinabove recited articles, generally comprises the steps of providing a polymer in particulate form and discrete pieces of foam material. The particulate polymer and foam pieces are tumbled to provide a heterogeneous mixture. In addition, a foaming agent may be utilized.
A quantity of discrete pieces of foam material are provided in a selected size and thereafter the particulate polymer and foam pieces are tumbled to provide a heterogeneous mixture. As hereinabove noted, a foaming agent may be a part of the heterogeneous mixture.
The heterogeneous mixture with plasticizer is introduced into a mold, which is thereafter heated, in order to cause melting of the polymer without melting of the foam. In this manner, the gelation of the melted polymer surrounds and encapsulates the foam particles and the heterogeneous mixture is not heated sufficiently to melt or degrade the foam pieces therein. In the case of the foaming agent, melting causes expansion thereof, thus producing voids within the mixture.
The melted polymer is allowed to gelate around the foam to cause a heterogeneous resilient cushion. Alternatively, the mixture may be passed through heated rollers which act as a continuous mold in order to form a sheet-like article or cushion.
In accordance with the present invention, a method for making a resilient cushion, which may take the form of any of the hereinabove recited articles, may generally comprise the steps providing a polymer in particulate form and adding a plasticizing oil thereto in a mixer or the like. Plasticizing oil is added in a quantity less than that to agglomerate the polymer particulate so that the resulting mixture of plasticizing oil and polymer particulate remains in a discrete granular, flake or particle form.
A quantity of discrete pieces of foam material are provided in a selected size and thereafter the particulate polymer and foam pieces are tumbled to provide a heterogeneous mixture. As hereinabove noted, a foaming agent may be a part of the heterogeneous.
The heterogeneous mixture with plasticizer is introduced into a mold, which is thereafter heated, in order to cause melting of the polymer without melting of the foam. In this manner, the gelation of the melted polymer surrounds and encapsulates the foam particles and the heterogeneous mixture is not heated sufficiently to melt or degrade the foam pieces therein. Some penetration may occur but is insufficient to degrade the foam. In the case of the foaming agent, heating causes expansion thereon, thus producing voids within the mixture.
The melted polymer is allowed to gelate around the foam to cause a heterogeneous resilient cushion. Alternatively, the mixture may be passed through heated rollers which act as a continuous mold in order to form a sheet-like article or cushion. When the foaming agent is utilized, the cushion includes voids along with the form pieces. Thus, the cushioning or resilient characteristics can be further tailored.
More particularly, the step of providing particulate polymer may comprise the providing of a triblock copolymer elastomer in particulate form and the plasticizer may be added in the form of a plasticizing oil.
Still more particularly, the step of heating the mold may include heating the mold to a temperature of between 150xc2x0 C. and about 200xc2x0 C.
Preferably, the step of providing discrete pieces of foam material includes providing a closed cell foam.
In an alternative embodiment of the present invention, a first amount of polymer in particulate form is mixed with a first amount of plasticizer and disposed in a mold. A second amount of particulate polymer is provided along with a second amount of foam pieces which are mixed or tumbled therewith, along with a plasticizer.
The second amount of copolymer along with the foam pieces and plasticizer are added to the mold without substantial commingling with the first amount of particulate polymer. Thereafter, the mold is heated to cause melting of both amounts of the polymer without melting the foam. The copolymer is allowed to cool and gelate with the first amount of melted polymer gelling into a homogeneous gel in the second amount of melted polymer gelling around the foam pieces to form a heterogeneous resilient cushion.
In addition, the present invention also encompasses a resilient cushion which is made in accordance with the hereinabove recited steps as well as a composition which when heated form a resilient material or cushion.
The present invention also includes the use of foaming agents in order to reduce the density of the resilient cushion. When utilized in particulate foam, the foaming agents expand to form voids within the resilient cushion.